Liver repopulation following hepatocyte transplantation is an important step to achieve successful therapy. Hepatocytes with an enhanced proliferation capacity will undertake liver repopulation more efficiently. Modification of hepatocytes in cell cycle can be achieved through controlling some cell cycle regulator proteins. As a key cell-cycle regulator of both G1/S phase transition and G2/M transition, the mammalian Forkhead Box M1 (FoxM1) protein is chosen in this application to improve the proliferation capacity of hepatocytes. The enhanced activation of FoxM1 accelerates hepatocytes to entry into S phase after liver injury of partial hepatectomy. Importantly, the hepatocytes with sustained expression of FoxM1 have no tendency to develop mutations and do not transform. We hypothesize that FoxM1 over-expression will allow faster and more extensive proliferation of hepatocytes in liver repopulation, and hence more efficiently repopulate recipient livers. The objective of this application is to generate hepatocytes with sustained expression of FoxM1 using non-viral vectors mediated gene delivery into hepatocytes. In Specific Aim 1, we will characterize the effect of sustained-expression of FoxM1 on hepatocyte proliferation during liver repopulation. In Specific Aim 2, we will generate genetically modified hepatocytes through non-viral vector mediated gene delivery. Our studies will for the first time shed light on the effect of FoxM1 on the hepatocyte proliferation during liver repopulation and enable us to characterize the effect of sustained FoxM1 expression on liver repopulation. In addition, we will use non-viral methods to achieve stable integration of cell cycle regulator into hepatocytes, which has not yet been used before. Knowledge gained from this project will be important for developing novel strategies for modification of donor hepatocytes used in transplantation therapy. [unreadable] [unreadable] [unreadable]